Abrading apparatus



Feb. 6, 1945.

W. L. KEEFER ABRADING APPARATUS Original Filed June 21, 1941 3 Sheets-Sheet 1 f nunuu.

Feb. 6, 1945. w. KEEFER,

ABRADING APPARATUS 3 Sheets-Sheet 2 Original Filed June 21 1941 FRI llllll I.

Z ul/ M4727? Arrears/s,

Feb. 6 1945. w. L. KEEPER 2,368,664

ABRADING APPARATUS Original Filed June 21, 1941 3 Sheets-Sheet 3 W/IA 727? 4 .KEEFE/F,

elm way Patented Feb. 6, 1945 ABRADING APPARATUS Walter L. Keefer, Hagerstown, Md., assignor to Pangborn Corporation, Hagerstown, Md., a corporation of Maryland Original applications March 10, 1938, Serial No. 195,138, now Patent No. 2,246,522, dated June 24, 1941, and June 21, 1941,.Serial No. 399,184, now Patent No. 2,329,203, dated September 14, 1943. Divided and this application April 30, 1943, Serial No. 485,197

3 Claims.

The present invention relates to abrading apparatus and more particularly to machines embodying a bladed rotor for propelling abrasive particles at high velocities against articles to be blasted. This application relates specifically to the balancing of the rotors of suchabrading apparatus, and is a division of my copending application Serial No. 399,184, filed June 21, 1941, now

Patent No. 2,329,203.

An object of the present invention is to provide a bladed centrifugal abradin-g machine including a transfer mechanism for supplying abrasive particles to the blades of the rotor, and a more specific object of the invention is to provide novel balancing means for the rotor employed in centrifugal abrading machines. Further objects will become apparent as the specification proceeds in connection with the annexed drawings, and from the appended claims.

In the drawings Figure 1 is a longitudinal section of abrading apparatus embodying the invention;

Fig. 2 is a front elevation of the apparatus shown in Fig. 1 as it appears when viewed from the left of that figure, with the housing partially broken away and the feed spout shown in phantom lines to more clearly illustrate the structure involved;

Fig. 3 is a sectional view taken on the line -3-3 of Fig. 2;

Fig. 4 is a front elevation of a portion of the rotary cup and the rotor of Figs. 1 and 2';

Fig. 5 is a fragmental side elevation of the cup and rotor of Fig. 4;

Fig. 6 is a longitudinal section of a form of blade for the rotor;

Fig. 7 is an end elevation of the blade shown in Fig. 6;

Fig. 8 is an enlarged front elevation of the cup I of the device of Figs. 1 and 2;

Fig. 9 is a section taken on, the line 9-9 of Fig. 8, looking in the direction of the arrows;

Fig. 10 is an enlarged front elevation of the deflector assembly employed in the apparatus of Figs. 1 and 2; I

Fig. 11 is a sideelevation of the structure shown in Fig. 10;

Fig. 12 is an enlarged fragmental view of thestructure shown in Fig. 1 taken partly in section, and illustrating an abrasive guard element cooperating therewith;

Fig. 13 is a section taken along the line l3l3 of Figs. 12 and 14 looking in the direction of the arrows;

Fig. 14 is a top plan of the abrasive guard element shown in Fig. 13;

Fig. 15 is a view similar to Fig. 3 but of a cast or one-piece rotor having means for balancing the rotor;

Fig. 16 is an elevation 0 showing the manner of positioning the balancing holes with reference to the rear face of the blade.

With continued reference to the drawings 10 wherein like reference characters have been employed todesignate like parts throughout the sev-- eral views thereof, the rotor which includes the blade assembly may assume any desired form,

but I have shown a rotor R secured to the hub 15 portion In of a, shaft H by means of a plurality of screws (not shown). A plurality of sectorshaped plates l2 are detachably secured to the face of the rotor R by a plurality of screws 13.

As seen more in detailin Fig. 3, plates' 12 2o arespaced apart on the rotor and their neighborin-g edges are beveled as at M so that they cooperate with the face of the rotor to define outwardly extending dovetail-shaped guideways. Blades B are provided with dovetailed shaped bases [5 which slidably cooperate with the guideways, and they are locked against outwardmovement by a plurality of detachablekeys I6 (Figs. 1 and 2) which are provided with lug portions l1. As seen in Fig. 2, keys l6 slidably fit into correspondingly shaped openings l8 provided in plates Each blade B is provided with an abrasivepro pelling face 20 having a raised portion or ridge 2| (for a purpose to be later described) and an abrasive guiding flange 22 for preventing the tion shown, key I6 may be moved to the left and removed from the rotor, and blades B may then be freely slid outwardly and removed from the.

apparatus for replacement. Therefore, when the blades are in place and are centrifugally urged 5 outward during operation, shoulders 23 positively prevent the keys from being'displaced. I The means I have provided for feeding abrasive over the inner ends of the blades will now be described. Rotor R. is provided with. a central opening 25 to receive the transfer mechanism. Seated in opening 25 is the base of what may be called a rotary cup C. The cup is provided with a closed bottom 26, and'it is secured to hub lfl by means of a cap screw 21. As seeniin Figs. 1, 4,. and 5, cup C is also provided with an f the structure of Fig. 1.5

lindrical portion 31.

locked .in place by nuts 53.

ing through the medial portion of the blade, for

a purpose that'willpresently appear. Flange 28 is provided with a plurality of axially extending grooves 29 (Fig. 9) for the purpose of causing a stationary layer of abrasive to remain in engagement with the inner surface of the flange at all times during operation, and the edge of the flange is serrated or notched forefiecting a discharge onto the inner ends of the blades in timed relationship thereto. A plurality of webs 3| (Figs. 8 and 9) are provided in the bottom of the cup for the purpose of strengthening-it.

Cup C is also provided with a pair of annular grooves 32 which function to assist the abrasive in lying centrifugally on the'flange at its-angle of repose, and to prevent it, in cooperation with the adjacent.portion of flange 28 of slightly reduced diameter, from prematurely discharging from the cup. Abrasive issuppliedto the cup by V means of a feed spout 35 which'is stationarily supported in a permanent position by any suitable means (not'shown). Spout '35 is provided with an inclined portion 36 which terminates in a cy- Portion 31 of the'feed spout, which is'thethird element of the assembly, projects into a deflector assembly D, v vhich is provided withan-inner gen- 1 erally cone-shaped-opening 38 and a cylindrical to its angle of repose therein. If the feed of abrasive tothe cup be arrested at this point, it will remain on the wall of the cup and will not discharge over-edge 33. jInFig. lgthe' surface of the abrasive when the oupis full is-indicated by the line 6!, and the angle'of repose, which is the angle between this line and a line parallel to the axisof rotation of the mechanism, is designated as'B2.

The deflecting assembly may assume various -forms, and in Fig. 1 it assumes the shape of a flange 63-which isso shaped at its outer periphery as to generallyconform to the surface of the cone-shapedllayer'of abrasive lying in the cup and is, accordingly,v a helix of increasing radius toward thedischarge edge of the cup.

- As more clearly seen in Fig. 11; the outer edge '64 of flange '63 is bevelled to substantially conthroat "39. 'Throat'3'9 is-of a diameter slightly greater'than terminal portion 3? of the'spout, with the result'that they fit sufiiciently closely j to prevent abrasive leakage between the parts,

and yet permitthe deflector assembly to be ad- 1 1 justed to vary the direction of discharge from' the 3 mechanism in a manner to be hereinafter pointed out. The deflector assembly is, accordingly, provided with a flaring'mouth through which the abrasive is discharged to the interior of cup "C.

The deflector assembly is, provided with a flange 5 4| which is secured to a'flange '42of a support 43 by means of a pair of'nut and bolt assemblies 44. Support 43 .extends through aligned 'aperturesin a wheel housing 45 and a liner 46, and is provided studs 49' secured -to housing 4.5, and a pair of nuts 5| .are threaded on studs 49 and cooperate with "flange 41 to rigidly maintain the latter in 1 contact with housing 45. If desired, nuts 5| may 1 be'loosene'dand support 43 rocked about the axis 1 of the mechanism to dispose the deflector assembly in various angularpositions to thereby vary the direction of the discharge from the rotor in a manner to be hereinafter pointed out.

In order to properly center the support and 1 accurately position the deflector assembly within the feed chamber, a plurality of set screws 52 are threadedinto the support and are adapted to be Accordingly, by loosening vnuts 53, set screws 52' may be threaded in or out to shift the support transversely of the axis of rotation (assuming nuts 5| have been loosened for this purpose) and the proper position accurately attained. I

1 Spout is supplied withabrasive in any suitable manner, but preferably metered and from agravity drop to impart the desired initialvelocity to the abrasive. The abrasivefed into the spout is quickly conveyedto the center of cup C an'dpromptly attains the fullperipheral speed ofthe 'cup. After ajpredetermined {quantity of abrasive has accumulated in thecup, it builds. up

j with a flanged]. Flange 41 is,provided with a 1 pair'of arcuate slots 48 which fit over a pair of form with the angle of repose of the abrasive lying in the cup. Flange 53 extends for approximately three quarters of a revolution 01'' about 270, with the 'result that the abrasive ,starts toundergo an axial deflection at a point 65, and is finally deflected over the discharge edge of the cup when it attains the point designated as 66. i

It has been found that it is not necessary 5 to plow through the abrasive on the rim of the cup, but-it is merely necessary to disturb or impart a slight initial movement thereto, because the cone of increasing radius compels the abrasive to continue. moving down the incline until it is discharged over the edge of the cup.: Therefore, the abrasive does not produce severe wear on flange 63. p v At point 66, flang '63 merges witha substantially cylindrical flange 67 which has little, if any, pitch and which may be termed a splash deflector. As seen in Fig. 1,flange. 6'! lines substantially in the plane of the-discharge portion of the edge 33, and. it functions'to prevent abrapredetermined point in thero-tation of the wheel and stray abrasive'is prevented by flange 6'! from leaving the cup elsewhere.

,The deflector in Figs. 1,. 2, 10, and 1 1 isshown as being adjusted to 'cause the abrasive-to be dislodged from the rim. ofthecup at approximately the twelve oclock position.. The abrasive is thrown substantially tangentially, as indicated by'the arrows fll'in Fig. 4, by reason of theifact that the abrasive possesses substantially noradial velocity and is traveling at the pel'ipheral speed of the cup at the'instaiitof discharge.

The abrasive discharges over the inner edges 33 of the cupC'in -a fan-shaped stream which is cut by-the'inner ends of the blades asthey successively pass the pick-up point. With the serrated or notched edge, the discharge from cup C. is intermittent 'or interrupted by providing the discharge edge 33 with a'plurality of axially projecting portions or baili'es. 33a, which preferably merge into-discharge edge 33 along -in-' clined surfaces 3317. As seen in Fig.4, surfaces 332) are disposed forwardly of each blade a considerable distance so that shortly after the. abrasive stream,.indicatedibyithe arrows 11,15, cut

, 30E by the inner ends of the blades, members-33a willaeffectna cut-ofiaofithe stream itself in approximately'45" of rotation dater. IIn otherwords, the .blades are .supplied=::with abrasive .only over an are of 45, and the. abrasive stream is then cut offzto prevent'it from. discharging into the remainder of the. large space behind each-blade.

:It'isalso apparent that as the. abrasive discharging from the :rim@ is .:traveling in. the same general direction as the inner. ends of the blades, it.iszpicked up :with 'a'minimum'impact. .:The abrasive picked. up'is. smoothly and continuously accelerated by :.the bladesand is discharged from the;outer ends thereof in a downward direction as .indicatedxby the arrows 12 (-Fig. 2). IIf.it'LiS desiredto changeithe direction of discharge, nuts 5| .are loosened andzsupport. iszrocked so-as to v If it is .desired todirect the discharge upwardly,

the support-43 may. beremoved, inverted and'replaced in the mechanismsolasto locatethe deflector assembly 180 from the position shown in Figs. 1. and 2, to effectjan up-ward,.discharge. of abrasive from the wheel. Also,. in special. installations, wher -ibis desired to "discharge theabrasive horizontally, the deflector may be secured tosupport43 atwan angle of '90. to. that shown, to effect dischargeof the abrasiveyeither to one side ofthe machine orthe other. It is, of course, understood that housingdimay. assume-various shapes depending upon the directionitisdesired to throw the abrasive-and other factors peculiar to the particular installation involved.

When the parts have become so Worn as to require replacement, nuts 5|. are removed and the deflector and spout assembly is removed from the machine. Nut and bolt assemblies 44 may then be loosened to permit the deflector assembly to be removed and replaced. Also, if the cup C requires replacement at this time, screw 2'! may be loosened to allow the cup to be removed.

In some installations where it is desired to direct a concentrated stream of abrasive upon the work, means may be employed to restrict the arcuate length, measured in degrees, of the discharge from the cup designated by the arrows H in Fig. 4, and in Figs. 12, 13, and 14 I have shown one form of means that may be employed for this purpose.

With continued reference to these figures, flange 4| of the deflector D is cut away for a portion of its periphery to allow a guard assembly G to be bolted securely to flange 42 of support 43. The guard assembly comprises a base portion 15 which is provided with a pair of openings 16. Bolt and nut assemblies cooperate with openings 16 and a pair of corresponding openings in flange 42 (not shown) tosecure the guard assembly in place on support 43. Formed on base 15 is a generally cylindrical main guarding surface 11 which overlaps the outer periphery of cup C and is provided with a bevelled surface 18 so as to allow it to fit closely to the cup.

In Fig. 13 the discharge edge 33 of the cup is indicated by a broken line and the main discharge of abrasive from the cup is designateddoy the arrows 19. Also illustrated in this figure are arrows 8| which indicate a small spray or premature discharge of the abrasive, and it is apparent that with guard 11 in place the stray abrasive indicated. by arrows BI is restrained from discharging into .the blades and rposstbly being prematurely discharged :.therefrom. The

stray=abrasive particles rebou n'd 'from t'he inner surface of tiguard $11 to join'the concentrated stream being discharged from. the-edge of cupjC.

*As pointed. out in connection withiFigS.'F1itOf-6,' inclusive,atheasplash.v deflector or flangesil prevents: any abrasive that is prematurely dislodged from thessurfaoe'of the'abrasivelying in the cup from :being discharged .onto the blades, 1 and :the action; ofxthe "flange is: enhanced by locatingzit some distance rearwar'dly of the. discharge edge 33-.-s01 that? it directly cooperates with the surface of the tabrasive lying on'flange28, with the result that the abrasivev can only escapefifrom the cup where :the flangeiifil is discontinued, namelyflbetween points .66;an'd 68 (Fig. I11). 'As the angle of repose assumed by the abrasive isrconstantjfor anygiven .set .offoperating conditions, and cannot .build .up beyond this angle.betweenfthelfdischarge'edge and. flange 61,:the latter,;accordingly, prevents. stray; abrasive: from .escapingifrom the cup.

It has been found in;practice,that:.all.1of the parts of the deflector assemblyjunction-cool:in

operation and .wearthereof is slow. 'Flangeifi'l only lightly bears against the surface of .athe abrasive, and as previously;pointedg,out,-:deflector flange orv helix 63" serves to. initially dislodge the abrasive, and the fact thatthe cone -is .of increasing radius in the direction-of the discharge edgeqcauses the abrasiveto tend to continue more down the-incline. ;I-Io.wever,,thexfull 1en gth:of

helix .63 controls the. movementof the abrasive across the conical surfaceuntil itisfinallycdischarged at edge 33. Wear of the helix-.isslow, however, because the major force impelling the abrasive toward the discharge edge is supplied by centrifugal force, and the helix merely exerts a minor or light following actionupon the abrasive.

As already described, a raised portion or ridge 2| is provided on blade B, and as seen in Fig. 6, it tapers off at 2la and merges into the blade surface 20 inwardly of the mid-portion of the blade. Ridge 2| is also provided with a sharpened inner end 2 lb which constitutes an elongation of the bevelled inner end 20a of the blade.

When a deflector assembly as shown in Figs. 10 and. 11 is used, the abrasive is discharged substantially parallel to the longitudinal axis of the blades and along the'center portion of the blade surface. Ridge 2|, causes the abrasive to be divided and distributed evenly on both sides of I ancing the rotor, I provide a series of apertures l2 in the blade face of rotor R immediately adjacent the rear face of the blade (the face that does notpropel the abrasive) To effect balancing, different sized plugs of materials of difierent densities, such, for instance, as plugs of lead and wood, are inserted in apertures l2.

-While it would seem that it would be suflicient to use varying quantities of a single material such as lead-in apertures [2, it has been found that this is unsatisfactory as some of the holes Y may not be entirely filled andothers may not have any material in it at all. In any hole which is not filled so that the surface of the contained material is flush, with the rotor disc surface, a gripping or stop surface for the abrasive that is continually flying about such a wheel is provided with the result that there is a rapid wear of the surface of the disc in the form of an elongated groove leading from the unfilled hole in a direction contrary to the direction of rotation of the disc. This wear'on the disc is such that its balance may be seriously thrown out in less than twenty-five hours operation, requiring that the wheel be removed from service and rebalanced.

While it may seem strange that by filling any empty or partially filled apertures with a relatively soft material such as wood, this wear can be prevented, this can be explained by the fact that the wood glazes rapidly and because it is flushwith the rotor disc surface, it eliminates any cavity or shouldered spot which might afford a purchase for the abrasive traveling thereover. The abrasive that would otherwise abrade the disc surface now slides freely thereover and does no damage.

The invention may be modified in other specific forms without departing from the spirit of essential characteristics thereof. The present embodiment is therefore to be considered in all-respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be em-' braced therein.

I claim:

1. A rotor for a centrifugal .abrading mechanism comprisinga disc having a, series of aper-- tures therein, and materials of different densities in said apertures to balance said disc for rotation, sufficient material being placed in each aperture to form a flush surface with the surface of said disc whereby no purchase surface is provided for flying abrasive.

2. In apparatus for propelling abrasive at an abrading velocity, a diSc shaped rotor arranged to rotate about the axis thereof, a plurality of blades on one side .of said rotor extending outwardly with respect to said axis to receive and impart an abrading velocity to said abrasive, said rotor being formed with at least one hole therein rearwardly of each blade on the same side of the rotor, and inserts of material in all of said holes to balance said rotor for rotation and having their outer faces flush with the adjacent face of the rotor whereby no purchase surface is provided for flying abrasive.

3. In apparatus for propelling abrasive at an abrading velocity, a disc shaped rotor arranged to rotate about the axis thereof, a plurality of blades on one side of said rotor extending outwardly with respect to said axis to receive and impart an abrading velocity to said abrasive, said rotor being formed with at least one hole therein rearwardly of each blade on'the same side of the rotor, and materials of different densities filling all of said holes to balance said rotor for rotation and flush with the rotor surface adjacent said holes whereby no abrupt change is provided on the surface of the rotor for engagement by flying abrasive.

WALTER'L; KEEFER. 

